In recent years, a configuration in which each of pixels has a charge holding portion isolated from a photoelectric conversion portion and a floating diffusion (hereinafter FD) has been considered for higher performance of a solid-state image pickup device. Firstly, the charge holding portion is provided in each pixel for realizing a global electronic shutter, as described in PTL 1. Secondly, the charge holding portion is provided in each pixel for expanding a dynamic range, as described in PTL 2. Thirdly, the charge holding portion is provided in each pixel for realizing a configuration having an analog-to-digital (AD) converter for each pixel, as described in PTL 3.
PTL 1 discloses a configuration of reducing noise by suppressing inflow of charges generated at a deep position of a semiconductor region into a charge holding portion. Specifically, PTL 1 discloses a configuration including a P-type well having a photoelectric conversion portion therein, a charge holding portion, and a P-type semiconductor layer that is provided under at least part of the charge holding portion via part of the P-type well and that has a higher impurity concentration than the P-type well.